1. Field of Invention
The present invention relates to a hole cutter for making holes in a metal sheet, in particular, to a universal hole cutter in the field of mechanics.
2. Related Art
In order for making holes in a workpiece or metal sheet, people have designed various kinds of hydraulic hole cutters. The existing hole cutters are generally consisted of a oil cylinder and a oil pump body in which the oil cylinder is directly fixed to the oil pump body. In these hole cutters, the oil cylinder could not rotate with respect to the oil pump body, so the oil pump body has to be move together when the position of the oil cylinder is to be changed. Therefore, the applicability of said hold cutters is relatively poor in different occasions of use.
To address the afore-mentioned problems, someone has designed a hole cutter in which the oil cylinder could move with respect to the oil pump body. For example, a hydraulic hole cutter is disclosed in a Chinese Patent CN02150961.1, comprising a cylinder, a hydraulic pump and a hose, in which both ends of the hose are respectively communicated with the cylinder and the hydraulic pump. During operation, the hose could be arbitrarily bended, and thus the position of the cylinder could be adjusted even in occasions with a smaller space, thereby effectively improving the applicability of the hydraulic hole cutter. However, the hose could not directly support the cylinder, which brings a problem of supporting the cylinder during use. In this regard, such a hydraulic hole cutter could not be conveniently used. In addition, the hose has such a limited strength that it tends to be detached or broken due to hauling during moving processes.
To this end, the applicant once disclosed a universal hole cutter in a Chinese Patent Application 200710036580.X, comprising an oil cylinder, an oil pump body and an oil storage body, in which the oil pump body is directly fixedly connected to the oil storage body and the oil paths of the two are in communication. A rigid movable linkage mechanism is provided between the oil cylinder and the oil pump body, via which the oil cylinder is communicated with the oil pump body and the oil cylinder could rotate with respect to the oil pump body. A pressure mechanism is set on the oil pump body, through which the power oil within the oil storage chamber is pressed into the oil cylinder. The oil thus pressed would drive the piston rod in the oil cylinder to move when it enters the oil cylinder. Since a male die is fixedly connected to the piston rod for making holes, the male die could be operated for making holes after it moves.
The pressure mechanism includes a movable handle and a stationary handle. The movable handle is hinged to the oil pump body, and the stationary handle is fixedly connected to the oil pump body. A plunger is connected with the movable handle. The plunger could be inserted into a plunger hole of the oil pump body. The plunger hole is communicated with the oil inlet passage. The plunger would move up and down repeatedly as the movable handle is turned up and down repetitively, so that the power oil within the oil storage chamber would be pressed into the oil cylinder through the oil inlet passage.
In the above universal hole cutter, the oil cylinder is made of iron and steel material. In this case, the oil cylinder has a large weight and thus could not be conveniently used. Moreover, the oil inlet bolt is welded to the oil cylinder, and the oil path between the oil inlet bolt and the oil cylinder is bended. According to such a configuration, the oil path tends to be blocked, and the welding site of the oil inlet bolt and the oil cylinder does not have an aesthetic appearance.